手寫防抖（debounce）
function debounce(fn, delay) {
? let timer;
? return function(...args) {
? ? clearTimeout(timer);
? ? timer = setTimeout(() => fn.apply(this, args), delay);
? };
}
手寫節(jié)流（throttle）
function throttle(fn, delay) {
? let flag = true;
? return function(...args) {
? ? if (!flag) return;
? ? flag = false;
? ? setTimeout(() => {
? ? ? fn.apply(this, args);
? ? ? flag = true;
? ? }, delay);
? };
}
合并數(shù)組
? ? ? ? let arr1=[1,2,3];
? ? ? ? let arr2=[4,5,6];
? ? ? ? Array.prototype.push.apply(arr1,arr2); //將arr2合并到了arr1中
求數(shù)組最大值
? ? ? ? Math.max.apply(null,arr)
判斷字符類型
? ? ? ? Object.prototype.toString.call({})
手寫 new 操作符
function myNew(Fn, ...args) {
? const obj = Object.create(Fn.prototype);
? const result = Fn.apply(obj, args);
? return result instanceof Object ? result : obj;
}
手寫 instanceof
function myInstanceof(obj, Fn) {
? let proto = obj.__proto__;
? while (proto) {
? ? if (proto === Fn.prototype) return true;
? ? proto = proto.__proto__;
? }
? return false;
}
手寫promise
// promise 構(gòu)造函數(shù)
function Promise (fn) {
? let that = this
? that.status = 'pending' // 存儲(chǔ)promise的state
? that.value = '' // 存儲(chǔ)promise的value
? that.reason = '' // 存儲(chǔ)promise的reason
? that.onFulfilledCb = [] // 存儲(chǔ)then方法中注冊(cè)的回調(diào)函數(shù)（第一個(gè)參數(shù)）
? that.onRejectedCb = [] // 存儲(chǔ)then方法中注冊(cè)的回調(diào)函數(shù)（第二個(gè)參數(shù)）
? function resolve (value) {
? ? // 將promise的狀態(tài)從pending更改為fulfilled，并且以value為參數(shù)依次調(diào)用then方法中注冊(cè)的回調(diào)
? ? setTimeout (() => {
? ? ? if (that.status === 'pending') {
? ? ? ? that.status = 'fulfilled'
? ? ? ? that.value = value
? ? ? ? that.onFulfilledCb.map( item => {
? ? ? ? ? item(that.value)
? ? ? ? })
? ? ? }
? ? }, 0)
? }
? ?function reject (reason) {
? ? // 將promise的狀態(tài)從pending更改為rejected，并且以reason為參數(shù)依次調(diào)用then方法中注冊(cè)的回調(diào)
? ? setTimeout(() => {
? ? ? if (that.status === 'pending') {
? ? ? ? that.status = 'rejected'
? ? ? ? that.reason = reason
? ? ? ? that.onRejectedCb.map( item => {
? ? ? ? ? item(that.reason)
? ? ? ? })
? ? ? }
? ? }, 0)
? }
? ?fn(resolve, reject)
}
then
Promise.prototype.then = function (onFulfilled, onRejected) {
? let that = this
? let promise2 ?
? onFulfilled = typeof onFulfilled === 'function' ? onFulfilled : v => v
? onRejected = typeof onRejected === 'function' ? onRejected : r => r
? ?if (that.status === 'pending') {
? ? return promise2 = new promise((resolve, reject) => {
? ? ? that.onFulfilledCb.push(value => {
? ? ? ? try {
? ? ? ? ? let x = onFulfilled(value)
? ? ? ? } catch(e) {
? ? ? ? ? reject(e)
? ? ? ? }
? ? ? })
? ? ? ?that.onRejectedCb.push(reason => {
? ? ? ? try {
? ? ? ? ? let x = onRejected(reason)
? ? ? ? } catch(e) {
? ? ? ? ? reject(e)
? ? ? ? }
? ? ? })
? ? })
? }
}
手寫Promise.all
Promise.all = function(promises) {
? return new Promise((resolve, reject) => {
? ? let results = [];
? ? let count = 0;
? ? promises.forEach((promise, i) => {
? ? ? Promise.resolve(promise).then(res => {
? ? ? ? results[i] = res;
? ? ? ? if (++count === promises.length) resolve(results);
? ? ? }).catch(reject);
? ? });
? });
};
手寫 Promise.race
Promise.race = function(promises) {
? return new Promise((resolve, reject) => {
? ? promises.forEach(promise => {
? ? ? Promise.resolve(promise).then(resolve).catch(reject);
? ? });
? });
};
手寫深拷貝（Deep Clone）
function deepClone(obj, map = new WeakMap()) {
? if (typeof obj !== 'object' || obj === null) return obj;
? if (map.has(obj)) return map.get(obj); // 解決循環(huán)引用
? let result = Array.isArray(obj) ? [] : {};
? map.set(obj, result);
? for (let key in obj) {
? ? if (obj.hasOwnProperty(key)) {
? ? ? result[key] = deepClone(obj[key], map);
? ? }
? }
? return result;
}
手寫數(shù)組扁平化（flat）
function flatten(arr) {
? return arr.reduce((prev, curr) =>
? ? prev.concat(Array.isArray(curr) ? flatten(curr) : curr),
? []);
}
手寫函數(shù)柯里化（Currying）
function curry(fn) {
? return function curried(...args) {
? ? if (args.length >= fn.length) {
? ? ? return fn.apply(this, args);
? ? } else {
? ? ? return (...args2) => curried.apply(this, args.concat(args2));
? ? }
? };
}
反柯里化
Function.prototype.uncurrying = function () {
? var that = this;
? return function () {
? ? return Function.prototype.call.apply(that, arguments);
? };
};
function sayHi() {
? return "Hello " + this.value + " " + [].slice.call(arguments);
}
let sayHiuncurrying = sayHi.uncurrying();
console.log(sayHiuncurrying({ value: "world" }, "hahaha"));
手寫?bind?函數(shù)
Function.prototype.myBind = function(context, ...args) {
? const fn = this;
? return function(...args2) {
? ? return fn.apply(context, [...args, ...args2]);
? };
};
冒泡排序
Array.prototype.bubleSort = function () {
? let arr = this, len = arr.length;
? for (let outer = len; outer >= 2; outer--) {
? ? for (let inner = 0; inner <= outer - 1; inner++) {
? ? ? if (arr[inner] > arr[inner + 1]) {
? ? ? ? //升序
? ? ? ? [arr[inner], arr[inner + 1]] = [arr[inner + 1], arr[inner]];
? ? ? ? console.log([arr[inner], arr[inner + 1]]);
? ? ? }
? ? }
? }
? return arr;
}[(1, 2, 3, 4)].bubleSort(); //[1,2,3,4]
選擇排序
Array.prototype.selectSort = function () {
? let arr = this,
? ? len = arr.length;
? for (let i = 0, len = arr.length; i < len; i++) {
? ? for (let j = i, len = arr.length; j < len; j++) {
? ? ? if (arr[i] > arr[j]) {
? ? ? ? [arr[i], arr[j]] = [arr[j], arr[i]];
? ? ? }
? ? }
? }
? return arr;
}[(1, 2, 3, 4)].selectSort(); //[1,2,3,4]
call實(shí)現(xiàn)
Function.prototype.newCall = function (context, ...parameter) {
? context.fn = this;
? context.fn(...parameter);
? delete context.fn;
};
let person = {
? name: "Abiel",
};
function sayHi(age, sex) {
? console.log(this.name, age, sex);
}
sayHi.newCall(person, 25, "男"); // Abiel 25 男
apply實(shí)現(xiàn)
Function.prototype.newApply = function (context, parameter) {
? if (typeof context === "object") {
? ? context = context || window;
? } else {
? ? context = Object.create(null);
? }
? let fn = Symbol();
? context[fn] = this;
? context[fn](...parameter);
? delete context[fn];
};
bind實(shí)現(xiàn)
Function.prototype.bind = function (context, ...innerArgs) {
? var me = this;
? return function (...finnalyArgs) {
? ? return me.call(context, ...innerArgs, ...finnalyArgs);
? };
};
let person = {
? name: "Abiel",
};
function sayHi(age, sex) {
? console.log(this.name, age, sex);
}
let personSayHi = sayHi.bind(person, 25);
personSayHi("男");
